Cost of living is immaterial

Haha. Really? I'd guess most people would disagree with you on that.

As for average wages in china here are a selection of figures that would suggest FTs are still doing alright in china.

100-200million still living in poverty (depends where you draw the poverty line though many seem to think that line is too low so this figure could be even higher). The CIA suggests the figure is 13.4% of the the population under the poverty line. Even the Chinese themselves admit 200million still live under it

http://articles.economictimes.indiatimes.com/2012-12-31/news/36079605_1_wealth-gap-li-keqiang-poverty-line

Average wages by province

http://www.chinadaily.com.cn/china/2012-07/06/content_15555503.htm

Even in the most expensive/developed cities teachers basic wage (ie not including housing, flight etc.) still exceeds the average.

The Chinese national bureau of statistics claims that the disposable income of an average Chinese household is just over 12,000rmb a year. Given that many FTs don't pay rent, utilities, etc. I'd say that they would have significantly more disposable income than this.